The foundation, formed in 1998, helps provide environmental protection groups with funding grants. The auction raised $30 million for the foundation's charity work. But this year's foundation coincided with the 20th anniversary of Titanic's release year — so naturally, it was the perfect place for the reunion.

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"Gangs back together. Now we're saving icebergs. Go figure," Billy Zane captioned an Instagram photo of himself with his costars at the time.

Winslet and DiCaprio are definitely friendship goals. They've praised each other plenty of times over the years, and it's clear they have a lot of respect for each other's talents.

"She is the consummate professional; she keeps pushing herself to an emotional truth when she's working," DiCaprio said of Winslet during an appearance on the Today show. "That's why I keep saying she's the best."

And at the 2016 Screen Actors Guild awards, Winslet was DiCaprio's biggest fan. That year, DiCaprio won the award for Outstanding Performance by a Male Actor in a Leading Role, thanks to his work in The Revenant.